Refactor SE2 and SE3 to use rotation-then-translation format

Sophus uses rotation-then-translation everywhere, gtsam is the same except for SE2 where it is flipped.

We should consider refactoring SE2 in that case, unless there are any consequences (and why gtsam uses the flipped convention for it). Aside from the function signature, the data order would also likely change then (x, y, c, s -> c, s, x, y).

_Originally posted by @mhmukadam in https://github.com/facebookresearch/theseus/pull/68#discussion_r801450549_